1. Field of the Invention
The present invention relates to an open end wrench, and more particularly to an anti-abrasion open end quick turn wrench.
2. Description of the Prior Art
A wrench, no matter open-end wrench or box-end wrench, is usually unable to rotate in a full circle, when it works in a restricted space, so the wrench has to be removed from the fastener (being rotated by the wrench) after rotating a certain angle, and then the wrench has to engage with the fastener and rotate another angle, and so on so forth. Therefore, it is inconvenient and low efficient. To solve this problem, various quick turn open end wrenches which are capable of rotating continuously in a single direction have been developed.
As shown in FIG. 1, a conventional open end quick turn wrench comprises a body 11, a handle portion 111 for gripping, and a drive portion 112 connected to the handle portion 111 for rotating a fastener 12. The drive portion 112 includes an engaging slot 113 for engaging with a head portion 121 of the fastener 12. The engaging slot 113 includes a first engaging surface 1131, a second engaging surface 1132 and an inner surface 1133 between the first and second engaging surfaces 1131, 1132. In the inner surface 1133 is defined a cavity 114 in which being disposed a retractable assistant engaging member 13 which is provided with an abutting surface 131 to be abutted against a lateral surface 1211 of the head portion 121 of the fastener 12.
The head portion 121 of the fastener 12 is slidably received in the engaging slot 113 of the drive portion 112, and the first and second engaging surfaces 1131, 1132, and the assistant engaging member 13 will clamp the fastener 12 to rotate it in the first direction (the clockwise direction). When the head portion 121 of the fastener 12 is received in the engaging slot 113, the inner surface 1133 allows the drive portion 112 to idly rotate back in the second direction (the counterclockwise direction) with respect to the head portion 121 of the fastener 12, so that the fastener 12 can be rotated continuously. However, this wrench also suffers from the following disadvantages:
Firstly, when the head portion 121 of the fastener 12 is completely received in the engaging slot 113, and the drive portion 112 rotates in the second direction with respect to the head portion 121 of the fastener 12, the angle 1212 of the head portion 121 of the fastener 12 will interfere with the inner surface 1133 of the drive portion 112, causing abrasion of the angle 1212 of the head portion 121, and even worse, all the angles 1212 might be seriously abraded so that the fastener 12 cannot be rotated by the wrench anymore.
Secondly, when rotating the open end wrench in the first direction (the clockwise direction), only the first engaging surface 1131 and the abutting surface 131 of the assistant engaging member 13 clamp two opposite lateral surfaces 1211 of the head portion 121 of the fastener 12, once the two opposite lateral surfaces 1211 clamped by the wrench are worn off, the open end wrench won't be able to engage with and rotate the fastener 12 anymore. The open end wrench has to be disengaged from the fastener 12 and rotate an angle, then the wrench has to be clamp other two opposite lateral surfaces 1211 that are not worn off, so that the fastener 12 can be rotated again.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages.